board-grouper-panel.c : reduce panel_min_brightness to 8

Signed-off-by: SkipXS <sskkiipp@gmail.com>
cpu-tegra3.c: adjust a bit towards nvidias defaults

Signed-off-by: SkipXS <sskkiipp@gmail.com>
scale3d.c: adjust towards nvidias defaults

Signed-off-by: SkipXS <sskkiipp@gmail.com>